This invention relates to a catalyzer support system for an internal combustion engine exhaust system and more particularly to an improved arrangement for supporting an exhaust treatment catalyzer in the exhaust system of an outboard motor.
The use of catalyzers for treating the exhaust gases of internal combustion engines is well known. A wide variety of catalyzer types have been employed for treating certain exhaust gas constituents prior to their release to the atmosphere so as to reduce the amount of harmful exhaust gas constituents. Although effective, there are many applications in which difficulties result in the provision of catalytic treatment of the exhaust gases.
A prime example of an application where catalyzer treatment is difficult is in outboard motors. As is well known, an outboard motor is an extremely compact device and offers a minimum amount of space and room for exhaust treatment. In addition, the exhaust system of an outboard motor includes a large area that is at least partially submerged during engine running conditions. When this amount of water is present in the exhaust system, it must be readily insured that the water cannot contact the catalyst bed as it will cause it extreme damage to it.
Furthermore, it is necessary to provide a good support for the catalyzer that will insure that a large portion or substantially all of the exhaust gases must pass into contact with the catalyzer. Frequently, the catalyzer is formed as a ceramic base and this requires careful support for the catalyzer.
It is well known that the temperature of the exhaust gases is quite high when running and that the catalyzer further elevates the temperature of the exhaust gases. Thus, there are substantial variations in temperature in the catalyzer and its support during various conditions of operation and ambient conditions. If these temperature variations are not accommodated, then large forces may be exerted upon the catalytic material as its temperature increases and because of the brittleness of the ceramic material, damage can result.
Frequently it is also a practice to provide some arrangement for cooling the area surrounding the catalytic bed so as to avoid the transmission of the high heat from the catalyst to the remaining components of the outboard motor, Frequently, water cooling jackets are employed for this purpose and this gives rise to further problems not only in the support for the catalyst, but the temperature variations which it experiences.
It is, therefore, a principal object to this invention to provide an improved catalyst arrangement for the exhaust gases of an internal combustion engine.
It is a further object to this invention to provide an improved catalytic system for an outboard motor.
It is a yet further object to this invention to provide an improved and compact catalytic system for an outboard motor that will insure full treatment of the exhaust gases and yet afford a support for the catalyst that will insulate it from thermal damage.